Conventional progressive addition lenses are lenses which have a far vision zone, a near vision zone, and a progressive corridor (or channel) there between. The progressive corridor provides a gradual power progression from the far vision zone to the near vision zone without dividing line or prismatic jump.
Generally, the dispensing of a particular progressive addition lens to a wearer involves selecting a progressive addition lens design from a range of available progressive addition lens designs based on certain visual requirements of the wearer.
The selection method may involve selecting a progressive addition lens having a peripheral design which the wearer is comfortable with and thus suitable for the wearer. However, although the selected progressive addition lens may have a peripheral design which is suitable for the wearer, other features, such as the inset, the corridor length, also called length of progression, may not be optimal for the wearer's visual requirements or non compatible with the wearer's spectacle frame.
Indeed, in a selection method which involves selecting a particular progressive addition lens surface design from a range of progressive addition lens designs, a progressive addition lens design having a suitable peripheral design together with other design features, such as the inset, the corridor length, which are related to the requirements of the wearer may not be available.